Search

In a preliminary version of the NA48 experiment at the CERN SPS, in which an iron-scintillator sandwich calorimeter was used as a photon detector, the ratio of K L → πμνγ and K L → πμν decays was measured. The branching ratio BR(K L →πμνγ, E γ ∗ ≥30 MeV )/(K L → πμν ) is found to be (2.08±0.17 +0.16 −0.21 )×10 −3 , where the first error is statistical and the second systematic. The result is in agreement with theoretical predictions.

A large sample of charged kaon decays in 2007 has been collected by the NA62 experiment at CERN SPS using the experimental setup of the former NA48 experiment. Its intense kaon beam provides an abundant source of tagged neutral pions in vacuum. A measurement of the electromagnetic transition form factor slope of the neutral pion from 1:05 × 106 fully reconstructed π0 Dalitz decays is presented. The obtained preliminary value a = (3.70 ± 0.53stat ± 0.36syst ) × 10−2 is the first 5.8σ observation of a non-zero slope in the time-like region of momentum transfer.K + → π+ vv is a theoretically very clean decay where indirect effects of new physics may be detectable. The NA62 apparatus has been significantly upgraded between 2008 and 2014 in order to measure the branching ratio of this decay with 10% precision. The NA62 experiment took data with the new setup in pilot runs in 2014 and 2015, reaching the design beam intensity. Results of first data quality studies in view of the 2016-2017 physics runs are presented.

The NA48/2 experiment presents a final result of the charged kaon semileptonic decays form factors measurement based on 4.28 million $K^{\pm}_{e3}$ and 2.91 million $K^{\pm}_{\mu 3}$ selected decays collected in 2004. The result is competetive with other measurements in $K^{\pm}_{\mu 3}$ mode and has a smallest uncertainty for $K^{\pm}_{e3}$, that leads to the most precise combined $K^{\pm}_{l 3}$ result and allows to reduce the form factor uncertainty of $\left | V_{US} \right |$. The NA48/2 experiment at CERN collected a very large sample of charged kaon decays into multiple final states. From this data sample we have reconstructed about 1663 events of the very rare decay $K^{\pm} \to \mu^{\pm} \nu e^{+} e^{-}$ over almost negligible background in the region with $m(e^{+}e^{−}$) above 140 MeV, which is of great interest in Chiral Perturbation Theory. We present the $m_{ee}$ spectrum and a model-independent measurement of the decay rate for this region.

The NA48 experiment at the CERN SPS has used K L 0 and K S 0 kaons for the precise measurement of the direct CP violation parameter Re ( ɛ ′ / ɛ ) . In 2002 it was re-designed as NA48/2 to search for CP violation in K ± → 3 π decays. This configuration has also allowed studying several rare decay processes of charged kaons to test chiral perturbation theory. With data samples of ∼ 10 6 K ± → π ± π − e ± ν decays, precise values of a 0 and a 2 , the isospin I=0 and I=2 s-wave ππ scattering lengths, are extracted with an unprecedented experimental precision. The same scattering lengths are also measured using ∼ 60 × 10 6 K ± → π ± π 0 π 0 decays where a cusp structure in the Dalitz plot has been observed for the first time.

The ratio R_K=Gamma(Ke2)/Gamma(Kmu2) provides a very powerful probe for the weak interactions structure. This ratio of decay rates is calculated with very high precision within the Standard Model but the corrections due to the presence of New Physics could be as high as 3%. The data obtained by the NA48 experiment at the CERN SPS accelerator during a 56 hours special run in 2004 has been analyzed.The precision of the preliminary result for R_K is two times better than the world average but is still insufficient to probe the existence of physics Beyond the Standard Model. Currently the experiment is taking data dedicated to the sub-percent precision measurement of R_K.

This Letter reports on a new high precision measurement of the form factors of the K L → π ± μ ∓ ν μ decay. The data sample of about 2.3 × 10 6 events was recorded in 1999 by the NA48 experiment at CERN. Studying the Dalitz plot density we measured a linear, λ + ′ = ( 20.5 ± 2.2 stat ± 2.4 syst ) × 10 −3 , and a quadratic, λ + ″ = ( 2.6 ± 0.9 stat ± 1.0 syst ) × 10 −3 term in the power expansion of the vector form factor. No evidence was found for a second order term for the scalar form factor; the linear slope was determined to be λ 0 = ( 9.5 ± 1.1 stat ± 0.8 syst ) × 10 −3 . Using a linear fit our results were: λ + = ( 26.7 ± 0.6 stat ± 0.8 syst ) × 10 −3 and λ 0 = ( 11.7 ± 0.7 stat ± 1.0 syst ) × 10 −3 . A pole fit of the form factors yields: m V = ( 905 ± 9 stat ± 17 syst ) MeV / c 2 and m S = ( 1400 ± 46 stat ± 53 syst ) MeV / c 2 .

We present a measurement of the ratio of the decay rates Γ ( K L → π + π − ) / Γ ( K L → π ± e ∓ ν ) , denoted as Γ K 2 π / Γ K e 3 . The analysis is based on data taken during a dedicated run in 1999 by the NA48 experiment at the CERN SPS. Using a sample of 47 000 K 2 π and five million K e 3 decays, we find Γ K 2 π / Γ K e 3 = ( 4.835 ± 0.022 stat . ± 0.016 syst . ) × 10 −3 . From this we derive the branching ratio of the CP violating decay K L → π + π − and the CP violation parameter | η + − | . Excluding the CP conserving direct photon emission component K L → π + π − γ , we obtain the results BR ( K L → π + π − ) = ( 1.941 ± 0.019 ) × 10 −3 and | η + − | = ( 2.223 ± 0.012 ) × 10 −3 .

After firmly establishing direct CP Violation in two pions decays of neutral kaons, the NA48 experiment at CERN-SPS has collected more than 1.6 billion of charged kaon decays into three charged pions, using a unique double beam technique which allows a high level of control on systematic effects. A preliminary result is presented on the direct CP violation Dalitz plot linear slope asymmetry parameter A g , that corresponds to more than an order of magnitude improvement in precision with respect to previous experiments.

The NA62 experiment at CERN SPS (Super Proton Synchrotron) accelerator aims at studying Kaon decays with high precision. The high resolution Liquid Krypton (LKr) calorimeter, built for the NA48 experiment, is a crucial part of the photon-veto system; to cope with the demanding NA62 requirements, its back-end electronics had to be completely renewed. The new readout system is based on the Calorimeter REAdout Module (CREAM) , a 6U VME board whose design and production was sub-contracted to CAEN , with CERN NA62 group continuously supervising the development and production phase. The first version of the board was delivered by the manufacturer in March 2013 and, as of June 2014, the full board production is ongoing. In addition to describing the CREAM board, all aspects of the new LKr readout system, including its integration within the NA62 TDAQ scheme, will be treated.

In data taken with the NA48 experiment at the CERN SPS in 1999, 730 candidates of the weak radiative hyperon decay Ξ0→Λγ have been found with an estimated background of 58±8 events. From these events the Ξ0→Λγ decay asymmetry has been determined to α(Ξ0→Λγ)=-0.78±0.18stat±0.06 syst, which is the first evidence of a decay asymmetry in Ξ 0→Λγ. The branching fraction of the decay has been measured to be Br(Ξ0→Λγ)=(1.16±0.05 stat±0.06syst)×10-3. © 2004 Elsevier B.V. All rights reserved.

The possibility of applying Feed-Forward Neural Network for particle identification in the experiment NA48 is investigated. It is shown that exploiting all the information available from the Liquid Krypton Electromagnetic Calorimeter, the efficiency for recognition of electrons and pions can be improved significantly. Using the method developed, it is possible to fulfill the NA48 programme for investigation of rare kaon decays without employing an additional experimental equipment.

The NA48 experiment at CERN detects concurrently the four decay modes into two pions of the long and short lived neutral kaons. During 1998 and 1999 data taking, statistics in each mode was increased by a factor eight, with respect to the 1997 published data. A new measurement of the double ratio of the four modes has been obtained from these data. This new result on the direct CP violation parameter Re(e′/e) is (15.0 ± 2.7) × 10−4 which, combined with the previous NA48 published result gives Re(e′/e) = (15.3 ± 2.6) × 10−4

The NA48 experiment at CERN was primarily designed to measure the value of Re( e ′/ e ), the parameter of direct CP-violation, from two-pion decays in simultaneous K L 0 and K S 0 beams produced at two different targets. Data for this measurement were taken from 1997 to 2001. The value obtained from the data taken in 1997–1999 is Re( e ′/ e )=(15.3±2.6)×10 −4 (Eur. Phys. J. 22 (2001) 231). The remaining data are being analyzed at present. In 2002 and the following years, rare-decay and CP-violation studies will be made in a high-intensity K S 0 beam (CERN/SPSC 2000-002) and in simultaneous beams of charged kaons (CERN/SPSC 2000-003), using basically the same apparatus. Photons from neutral-pion decays are detected by a liquid-krypton calorimeter. For the Re( e ′/ e ) measurement it is very important to suppress the huge background from K L 0 →3π 0 decays, which requires very good spatial, energy and time resolution.

The NA48 experiment at the SPS accelerator at CERN aims at measuring the parameter of direct CP-violation, e′/e with an accuracy of 2×10−4. Neutral kaons are produced at two targets located at different distances from the detector, thus creating a “Klong” and a “Kshort” beam. The experiment measures the decays of kaons from these two beams into two neutral or two charged pions. The detection of photons from neutral-pion decay is achieved by means of a liquid-krypton calorimeter. In order to suppress the huge background from KL0→3π0 decays, very good spatial, energy and time resolution are mandatory. The charged mode (K0L,S→π+π− decays) is measured with a spectrometer consisting of four drift chambers and a magnet. Decays from the two beams are distinguished by tagging the protons impinging on the second target by means of a scintillator array. Excellent time resolution and high efficiency are indispensible. Moreover, both the detector and the associated electronics operate in a high-radiation environment. This has given rise to specific problems, and the solutions adopted by NA48 are presented.

The direct CP violation parameter Re(epsilon'/epsilon) has been measured from the decay rates of neutral kaons into two pions using the NA48 detector at the CERN SPS. With 3.3 million KL->pi0pi0 events collected during the 1998 and 1999 running periods, a result of Re(epsilon'/epsilon) = (15.0 +- 2.7)x10-4 has been obtained. The result combined with the published 1997 sample is Re(epsilon'/epsilon) = (15.3 +- 2.6)x10-4.

A new measurement of ℛe(∊′/∊) by the NA48 collaboration using data collected in 1998 is presented. The preliminary result is ℛe(∊'/∊) =(12.2±2.9 ( stat )±4.0 ( sys )) ×10-4. The combination with the previous measurement using the 1997 data yields ℛe(∊′/∊)=(14.0±4.3)×10-4. This result confirms the existence of direct CP violation. The uncertainty on this measurement will be improved in the future.

The NA48 experiment at the CERN SPS accelerator aims to measure $\Re(\epsilon'/\epsilon)$, the direct CP violation parameter in $K^{0} \to 2\pi$ decays, to the precision of $2 \times 10^{-4}$. In the year 1999, the NA48 collaboration has published its first measurement based on the 1997 data. The presented result is a preliminary measurement from data collected in the 1998 run which contain 2.5 times more $K_{L} \to 2\pi^{0}$ decays than the 1997 data. A combined result of $\Re(\epsilon'/\epsilon)=(14.0 \pm 4.3) \times 10^{-4}$ has been obtained.

The NA48 experiment at CERN has performed a new measurement of the CP-violating parameter Re(ϵ′/ϵ). The experiment collects KL and KS decays into π0π0 and π+π− from the same decay region simultaneously. A new measurement of the Re(ϵ′/ϵ) parameter based on the data collected during the 1998 run is presented. The preliminary result for the Re(ϵ′/ϵ) based on data collected in 1997 and 1998 is (14.0±4.3) · 10−4.

The NA48 experiment at CERN has performed a measurement of direct CP violation in the neutral kaon system, based on data collected in 1997 and 1998. The preliminary result for the parameter Re(ϵ′/ϵ) is (14.0±4.3)×10 -4

We present the first observation of the decay KS→π+π−e+e− based upon the data collected in 1998 by the NA48 experiment at CERN. We have identified a clean sample of 56 events with negligible background contamination. Using KL→π+π−π0D decays as normalization sample, the branching ratio is measured to be BR(KS→π+π−e+e−)=[4.5±0.7(stat)±0.4(syst)]×10−5. This result is in good agreement with the theoretical expectations from the mechanism of inner bremsstrahlung.

A part of the LKr calorimeter data acquisition system of the NA48 experiment (a precision measurements of e/e′ in CP violating; K 0 →2π decays) is described. The experiment runs on the SPS north area in CERN. This paper presents some aspects of controlling the NA48 readout process based on commercial RIO 8260 RISC processors, which were used as a core for maintaining control algorithms. Several RISC processors were equipped with custom-made VME mezzanine boards providing interfacing, pre-processing and data formatting. These mezzanines are subjects of this paper. They are: RIO-TIC/DAT – time stamp distributor and buffered DT-bus interface, FOL-RIO – optical data formatter and event merger and “TAXI receiver” – handling trigger data of the NA48 Level 2 trigger supervisor. Also the interface between DT-bus and S-link/PCI is described.

The NA48 experiment at the CERN SPS aims to measure the parameter $\Re(\epsilon'/ \epsilon)$ of direct CP violation in the neutral kaon system with an accuracy of $2 \times 10^{-4}$. Based on the requirements of: \\\\ * high event rates (up to 10 kHz) with negligible dead time;\\ * support for a variety of detectors with very wide variation in the number of readout channels;\\ * data rates of up to 150 MByte/s sustained over the beam burst;\\ * level-3 filtering and remote data logging in the CERN computer center; \\\\ the collaboration has designed and built a modular pipelined data flow system with 40 MHz sampling rate. The architecture combines custom-designed components with commercially available hardware for cost effectiveness and flexibility. To increase the available data bandwidth and to add filtering and monitoring capabilities, the original custom-built event builder hardware has been replaced by a farm of 24 Intel PentiumII based PCs running the Linux operating system during the shutdown between the 1997 and 1998 data taking periods. During the data taking period 1998 the system has been successfully operated taking ca. 70 Terabyte of data.

A new precision measurement of the $\Xi^0$ mass has been performed at the NA48 experiment at the CERN SPS. The value obtained is [1314.82 $\pm$ 0.06 (stat.) $\pm$ 0.2 (syst.)]\,\mbox{MeV/c} $^2$ . The branching ratios of $\Xi^0$ radiative decays have been measured as: Br $(\Xi^0\rightarrow\Lambda\gamma)=[1.90\pm0.34 (stat.) \pm0.19 (syst.)] \cdot 10^{-3}$ and Br $(\Xi^0\rightarrow\Sigma^0\gamma)=[3.14\pm0.76 (stat.)\pm0.32 (syst.)]\cdot 10^{-3}$ .

We describe the part of the data acquisition system of the NA48 experiment (A precision measurements of e / e ′ in CP violating; K 0 →2π decays), located on the SPS north area in CERN. This part controls the readout electronic for liquid krypton calorimeter based on the CPD modules. The CPDs are placed in 30 Fastbus crates chained into four Fastbus clusters, which are entirely galvanic isolated. The timing and synchronization of the readout process is provided by an 80 MHz clock train which contains various gaps of different size. For purpose of controlling the LKr readout, two types of Fastbus modules were designed and fabricated in high volumes: isolated clock fanout and optoisolated cluster interconnect.

The status of the CERN NA48 experiment aimed at measuring the direct CP violation in the K 0 − K − 0 system is presented. The performances of the apparatus are discussed for the 1997 and 1998 data taking periods.

A first level trigger system based on a 40 MHz digital pipeline has been developed for the CERN NA48 experiment, aiming at measuring CP violation in K/sup 0//spl rarr/2/spl pi/ decays. The outputs of the 13340 cells of the 10 m/sup 3/ liquid krypton calorimeter are summed into 64 X and 64 Y projection strips and continuously digitised with 40 MHz FADCs. This information is used to reconstruct at each clock cycle and for the two calorimeter projections, the number of clusters, the impact time of each of them (with a precision of about 3 ns), their total energy and the first and second moments of the energy distribution. Based on the quantities listed above, a programmable look-up table system subsequently computes online the longitudinal position of the kaon decay vertex and performs an event selection. The system is described.

The NA48 experiment is installed at the CERN SPS. Its main goal is the measurement of direct CP violation in the neutral K to two pion decays. Detector performances obtained in test runs in 1996 and early 1997 are presented.

This article describes the NA48 experiments at CERN, in particular the layout of the simultaneous Kaon beams, the K S -tagging, the magnetic spectrometer and the electromagnetic liquid krypton calorimeter. Some results from early runs, including rare decays, are presented.

A fully pipelined 40 MHz “dead-time-free” trigger system for neutral K 0 decays for the NA48 experiment 2 at CERN is described. The NA48 experiment studies CP-violation using the high intensity beam of the CERN SPS accelerator. The trigger system sums, digitises, filters and processes signals from 13 340 channels of the liquid krypton electro-magnetic calorimeter. In 1996 the calorimeter and part of the trigger electronics were installed and tested. In 1997 the system was completed and prepared to be used in the first NA48 physics data taking period.

A drift chamber readout system for a bout 8000 channels with continuous sensitivity, i.e. concurrent data recording and readout, is described. Drift times are measured in bins of 1.56 ns with respect to a continuously running 40 MHz clock. The clock interval of 25 ns is divided into 16 bins by means of a 16-element delay chain. The length of this chain is linked to the clock interval by a phase-locked loop. An ASIC chip was developed to perform time measurements and data storage for 16 channels. In an asynchronous readout of this chip, data are tranferred to intermediate buffers, for use in a first-level trigger and eventual final readout. The design of the electronics is described and results from data-taking runs are presented.

First test results are reported from the NA48 K s tagging system. The system consists of two subdetectors. One samples the passing time of each proton which will hit the K s target ( tagging detector ), the other one measures the event time of a charged Kaon decay ( hodoscope for charged decays ). The tagging detector was read out with a FADC system operating with a sampling frequency of 480MHz. A time resolution of 182ps and resolving of double pulses down to 4ns could be achieved.

The NA62 experiment at CERN will study the very rare decay, K+ π+ ννbar. To reject the K+ π+ πo background, the detector must be hermetic to photons with a single-photon inefficiency of 10−5 for energies above 1 GeV. Three detectors will cover the experiment acceptance: the Liquid Krypton calorimeter from the NA48 experiment, the Large Angle Veto (LAV), and the Small Angle Calorimeter (SAC). The LAV is composed of 12 ring-shaped veto stations positioned along the NA62 vacuum decay tank. Each ring consists of 160 to 256 lead glass blocks, for a total of nearly 2500 blocks, each weighing ∼22 Kg. The construction of the LAV rings started in 2009 and is still ongoing. During the assembly process, each block undergoes a preparation phase which includes the measurement of all properties related to the block's light yield and to the read-out electronics. To regulate and monitor the entire assembly line, we have developed a MySQL-based DB system where all data produced during the assembly process are stored. A web-based user interface offers several functions such as input of block-related data, monitoring of the assembly status of each block, verification of the measurement process, and visualization of the overall status of the LAV production. Data stored in the DB are used both during the assembly process and to configure the LAV DAQ system. This paper will describe the criteria used to create this DB and will provide details about its technical implementation.

Channeling of a 450 GeV/c proton beam through a bent silicon crystal has found a novel application to the production of simultaneous particle beams. A pair of simultaneous, nearly-collinear beams of long- and short-lived neutral kaons has thereby been derived. These beams form an integral part of an experiment, NA48, at CERN, designed to measure the CP-violation parameter ϵ′ ϵ with high precision.

We discuss construction details of large drift chambers for the NA48 experiment at CERN. Preliminary measurements on their performance are also presented.

We have built and tested a beam profile monitor for the proton beam directed to the K s target of the NA48 experiment at the CERN SPS. The beam has a small cross-section of 3 × 6 mm 2 and a total flux of 3 × 10 7 protons per pulse. The counter is constructed from two orthogonal sets of 20 square scintillating fibers covering an active area of 10 × 10 mm 2 . The fibers are read out in parallel with a 64-channel photomultiplier. The beam position can be measured in real-time with a resolution of 55 μm.

The NA62 experiment [1] at the CERN SPS (Super Proton Synchrotron) accelerator studies the ultra-rare decays of charged kaons. The high-resolution Liquid Krypton (LKr) electromagnetic calorimeter of the former NA48 experiment [2] is a key component of the experiment photon-veto system. The new LKr readout system comprises 14,000 14-bit ADC acquisition channels, 432× 1 Gbit Ethernet data request and readout links routed by 28× 10 Gbit network switches to the experiment computer farm, and timing, trigger and control (TTC) distribution system. This paper presents the architecture of the LKr readout and TTC systems, the overall performance and the first successfully collected experiment physics data.

The NA48 Collaboration has already investigated rare hyperon decays in special high intensity runs during 1999 and 2001. For 2002, the changes to the NA48 beam line will allow systematic studies on neutral hyperon decays at sensitivities greatly in excess of current values. The programme of data-taking and the range of analyses are discussed.

The final design of the NA48 tagging system is described and a discussion of the 1992 test run results for the detector prototype is presented. A time resolution of about 90 ps is obtained with standard electronics, and a light yield of 300–400 p.e. is measured. A 450 MHz 6 bit FADC system has been designed and tested. This system has shown an intrinsic time resolution of 50 ps, and a double pulse resolution of 7 ns. A high precision alignment procedure allows to achieve a detector efficiency consistent with 100%. The technical and mechanical features of the design are well suited for the purpose of the experiment.

The NA62 experiment [1] at CERN SPS (Super Proton Synchrotron) accelerator will be focused on precision tests of the Standard Model via studies of ultra-rare decays of charged kaons. The high resolution Liquid Krypton (LKr) calorimeter of the former NA48 experiment [2], together with other detectors, will provide a photon-veto with hermetic coverage from zero out to large angles from the decay region. The old backend electronics [3] does not satisfy the NA62 specifications and the study of a new readout system began in 2008. This paper presents the Calorimeter REAdout Module (CREAM), an upgrade project for the backend part of the LKr data acquisition chain [3]. The CREAMs will provide 40 MHz sampling of 13248 calorimeter channels, data buffering during the SPS spill, zero suppression, and programmable trigger sums for the experiment trigger processor.

A measurement of the [ital CP]-violation parameter Re([var epsilon][prime]/[var epsilon]) has been made using the full E731 data set. We find Re([var epsilon][prime]/[var epsilon])=(7.4[plus minus]5.2[plus minus]2.9)[times]10[sup [minus]4] where the first error is statistical and the second systematic.

The new measurement of branching ratio of the radiative decay Ξ 0 → Σ 0 γ is presented. This measurement has been performed in the NA48 experiment at the CERN SPS. Using data collected during a special high intensity run at the end of 1999, we determined the following preliminary result: Br (Ξ 0 → Σ 0 γ) = (3.7 ± 0.5) × 10 −3 .

The NA48 experiment at the CERN SPS measures the direct CP violation parameter Re( e ′/ e ) in the neutral kaon system with an intended precision of 2×10 −4 . Thus, the data acquisition system has to handle peak rates up to 150 MByte/s during a 2.5 s beam burst and flat rates up to 20 MByte/s during on-line processing. The NA48 on-line PC farm includes 24 PentiumII-266MHz PCs connected via switched fast ethernet network. This farm receives data from the detector systems and performs event building. Afterwards the data are transferred via an optical gigabit ethernet link to the NA48 central data recording system at CERN computer center. In addition, trigger and checking processes can be applied. The software on the farm is implemented as client/server applications and represents a highly flexible, fail safe, and scalable system. During data taking, in 1999, 100 TByte were collected, processed, and stored by the acquisition system with an overall efficiency of 99%.

The NA48 experiment for a precision measurement of the CP violation parameter ϵ′ ϵ in K 0 → 2 π decays will require a fast electromagnetic calorimeter with excellent energy and time resolution. A quasi homogeneous calorimeter using liquid krypton and a fast readout with 40 MHz FADCs is proposed. A prototype with 400 kg of liquid krypton was built and tested in an electron beam. Results for the energy, space and time resolution of this prototype are given.

The NA62 experiment at CERN, aiming to start data taking in 2011, intends to measure the branching ratio of extremely rare kaon decays. The existing Liquid Krypton (LKr) calorimeter of the NA48 experiment will play an essential role in the new experiment. For this reason a program for the consolidation of the LKr read-out system was launched in 2006. The first part of the program consists of updating the existing data acquisition system to a modern more reliable technology using Gigabit Ethernet and PC-farm. In the second stage the readout event rate has to be increased from 13 kHz to 1 MHz. Methods to do this, while keeping much of the existing analog system, are discussed.

Semileptonic decays of charged and neutral kaons, KL → π±e∓νe (Ke30), KL → π±μ∓νμ (Kμ30) and K± → π0e±νe (Ke3±), were used to study the strangeness‐changing weak interactions of hadrons. High statistics data samples of reconstructed events recorded by the NA48 experiment were analyzed to obtain the Dalitz plot densities. Investigations of all possible Lorentz‐covariant couplings were performed and vector f+(q2), f0(q2), scalar fS and tensor fT contributions to the weak interaction were measured. Assuming only vector‐axial couplings both the linear and quadratic terms of the momentum transferred expansion of the vector form factors were obtained. Alternatively, a fit to a pole form factor was performed.

The beam and detector, used for the NA48 experiment, devoted to the measurement of Re (ε{lunate}′ / ε{lunate}), and for the NA48/1 experiment on rare KS and neutral hyperon decays, are described. © 2007 Elsevier B.V. All rights reserved.

Several recent results from the NA48 experiment are presented: a measurement $|\eta_{+-}|$, search for CP violating phenomena in $K^\pm\to3\pi$ decays, and a measurement of $|V_{us}|$., Comment: A talk given at the 2007 Europhysics Conference on High Energy Physics. 3 pages